Sliding door lock



R. ADAMS SLIDING DOOR LOCK 3 Sheets-Sheet 2 ARTHUR A. ADAMS IN VEN TOR.

' Attorney July 1, 1958 Filed July 6, 1954 y 1 8 A. R. ADAMS 7 2,841,431

SLIDING DOOR LOCK Filed July 6, 1954 3 Sheets-Sheet 3 FIG. /0.

ARTHUR 1?. ABA MS INVENTOR ATTORNEY 2,841,431 Patented July 1, 1958 Unite States Patent Ofiice SLIDING noon LOCK Arthur R. Adams, Pasadena, Calif., assignor to The Safe Padlock and Hardware Company, Lancaster, Pa., a corporation of Pennsylvania Application July 6, 1954, Serial No. 441,265

16 Claims. (Cl. 292-17) This invention relates to separable means for holding parts together, and particularly to improvements in mechanism for holding the parts locked after they have been brought together. The invention is particularly adaptable in a device for holding a sliding door in closed position in a door frame. The invention may, however, be utilized in other applications where it isdesired to releasably latch two parts together and at times topositively lock the parts together. The invention may conceivably find application in connection with seat or cargo tie-downs; as a holding device for conveyor belts, or for shipping pallets; or it maybe used as a small luggage or suitcase catch. The invention might be utilized in other comparable applications.

This invention is a continuation-in-part of this inventors earlier filed application, Serial No. 387,399, filed October 21, 1953, now U. S. Patent No. 2,807,489.

The earlier invention dealt with a latching and locking device adapted to be employed for yieldably holding or locking a sliding door or the like, in closed position in its frame. The present invention is concerned primarily with improvements in the mechanism for positively locking the parts together and, in general, improving the arrangement of parts to facilitate their manufacture, assembly and installation.

The structure of the invention involves. generally a compressible-expansible membenwhich may be in the form of a projection or pin having a knob or head which is adapted to be received in areceptacle in the other of the parts to be attached. A retractable locking bar is provided having a tongue cooperable with the compressible-expansible knob or head in a manner to prevent its being compressed or contracted, and to thereby prevent its withdrawal from the receptacle so as to positively lock the parts together. This invention provides improvements, particularly in the mechanism for operating the locking bar, wherein positively defined locked and unlocked positions are provided. These positions are provided uniquely constructed and adapted spring detents of the ball type associated with the locking bar so that the locking bar is never in an intermediate or undetermined position, but rather, it and its associated operating knob are either in locked or unlocked position.

The locking and unlocking operation of the mechanism as referred to above, is effected by a manual operating knob which is mounted in an assembly carried by a cavity in the sliding door, for example. The operating knob is associated with escutcheon cups or plates carried in the cavity in the door, and the parts are so designed and arranged as to be reversible, that is, the escutcheon cups or plates can be interchanged between opposite sides of the door so that the locking knob can be on either side of the door without any change or other rearrangement of parts. The invention is in this respect highly adaptable and versatile, and as will appear hereinafter, is otherwise adaptable to various widths and thicknesses of doors and parts and to various configurations of parts to be attached.

It is accordingly an object of the invention to provide improvements in a latching and locking device of the character described, wherein normally separable parts are latched by a resilient projection member being received in a receptacle and the parts are positively locked by a spring detent controlled locking bar cooperable with the resilient projection in a manner to prevent its being contracted and to thereby positively lock it in the receiving receptacle.

It is another object of the invention to provide a releasable latching and locking device for separable parts, having a resilient projection extending from one part into an opening in the other part and having positive locking means comprising a locking bar within the resilient projection, and operable to prevent contraction of the projection for locking, the locking bar being operable between positions determined by a ball detent mechanism provided between the locking bar and adjacent portions of the resilient projection.

Another object of the invention is to provide a device of the character described, wherein the resilient projection is a tubular member operating within a sleeve, the locking bar extending longitudinally within the projection and sleeve, spring detents being provided by a pair of ball members seated in complementary openings in the locking member and sleeve, the spring force being provided by a resilient split ring surrounding the sleeve and having complementary openings engaging the outer surfaces of the ball members so as to urge them inwardly against the locking bar.

Another object is to provide an improvement in a device as set forth in the foregoing, providing for reversibility of the manual operating mechanism for the locking bar; that is, the assembly carrying the operating knob may be reversed in the door cavity so that the knob is on either side of the door, the locking bar having symmetrical lever engaging portions extending from opposite sides of the bar, so that the operating knob when on either side of the door, can assume the same relative position with its operating lever engaging the locking bar for proper operation,

Another object is to provide a device as in the foregoing, providing two locking bars actuatable from individual operating knobs on opposite sides of the door.

Further objects and numerous additional advantages of the invention will become apparent from the following detailed description and annexed drawing, wherein:

Fig. 1 is a sectional plan view showing a portion of a door frame and the adjacent edge of a door, the view being taken along the line 1-1 of Fig. 4;

Fig. 2 is a view of the front escutcheon cup and operating knob;

Fig. 3 isa view of the back escutcheon cup;

Fig. 4 is a view partly in section of a part of the back face of the door and frame showing the parts in operative relationship;

Fig. 5 is a detail View taken along the line 5-5 of Fig. 6;

' Fig. 6 is a view similar to that of Fig. 4, showing the projecting pin in section;

Fig. 7 is a detail view of the locking bar;

Fig. 8 is a detail view of the latching pin or projection;

Fig. 9 is a detail view of the dished plate having the receptacle opening, in which the projection is received; and

Fig. 10 is an exploded view of a modified form of the invention providing for locking from either side of the door.

Referring now more in detail to Figs. 1 and 4 of the drawings, numeral 10 designates the edge portion of the front face 11 of sliding door 12 in engagement With:.a frame member 13. The door 12 is shown in closed posi be firmly held in place.

' b h ou hgthe r a 28 n ,the late o wa h r?" 'of the receptacle27. v j I tion, that is to say, its front edge face 14'is in'enga gement with'the edge face 15 of the member 13.

The invention provides a-projection 18 which projects 7 from an assembly carried in the door 12 and which is received in a receptacle in the frame 13. I The projection 18 is adapted to be releasably latched in the receptacle,

or positively locked therein. The mechanism for accomplishing the locking action is within a cavity 20in the door 12, this cavity being circular and having engaged therewith flanged front and back escutcheon cups 22 and 23,respectively. Within the front escutcheon cup 22 is a manual operating knob 25 for the locking mechanism. Thestructural assembly of Fig. 1 will be referred to more in detail ,presently.

' The framemember 13 has therein a receptacle 27 having :an opening 28 which receives the projection 18 carried' by the door 12 :in a-position'projectin g from its edge face 14.

In this embodiment of the invention the projection 18 is in the form of a rounded knob 29 -ar-..

ranged to expand in the receptacle 2 7 beyond the opening 28 so that removal of the knob 29 from the receptacle 27 requires contraction of the knob 29. a

As best shown in Fig. l andFig. 4,,the receptacle 27' comprises a dished washer 30 and means-for supporting the washer 30 in a shallow recess 31 formed by a wood bit in the edge face;15 of the frame member 13. The means for holding the dished washer 30 in the recess 31 comprises a shallow circular dished member 32 having a cylindrical Wall 33 and a radially extending wall 34,

there being openings for the passage of screw's'35 in both the members 30 and 32 so that the receptacle 27 will 7 A hole 36 is drilled inwardly from the bottom of the recess 31 to accommodatethat portion of the knob 29 which projects inwardly from the receptacle 27. a a

" As best shown in Figs. 6 and 8, the projection 18 com prises a head or knob 29 and 'a shank 37, which shank;

37 extends into a sleeve 39, Figs. 4 and 6, which is extended through an openingp which connects the edge face 14 of the door 12 with the larger opening or cavity 20, which is bored through the edge portion 10 of the door from the front face 11 to the rear face thereof, as

' shown in Figs. 1 and 4, the axisof the opening 20 being perpendicular to the axis of the opening 40 and intersecting thepsame. The sleeve 39 has on its front end a dished flange 42 which is countersunk into the edge .face 14 of the door 12, and screws 43 are extended through the flange 42, the inner threaded ends 45 being threaded into a plate 46 which rests in cavity 20 at the end'of opening 40. This prevents the pulling out of the sleeve 39 from the door execept by breaking out of the wood between the edge face 14 of the door 12 and Numeral 54 designates generally a locking bar which -is provided for holding the knob 29 in expanded 'condi-' tion so that it cannot be pulled out of the opening 28 Q of the receptacle 27, thereby preventing the door from 'being opened from the position in'which itis shown in Figs. 1, 4 and 6. The locking bar 54 normally occupies a position within the sleeve 39. and within the pin 18, as will presently be described (see Figs. 4 and 6). locking bar is shown indetail injFig. 7, and it is formed by stamping from sheet metal. The locking bar is formed 7 from two similar pieces as shown, which are broader at the left end as seen in Fig.7, and are attached by a swaged rivet as ,shown at 55, the two pieces having a oppositely extending bifurcations or fingers; as shown at 56 and 57. Atthe'opposite end'the 'locking bar has a narrow tip, as indicated at 59, which is adapted to. ex-

tend into the slot between the two halves 29a and 29b of r the head of the pin 18. The two pieces of the locking a bar are narrowed and offset at. the end as shown, one

' to its tip 59. The;lock.ing bar 54 may be advanced and retracted within the sleeve 39 'inorder to moveit s tip into and out of the slot between the halves-29a and 29b of the pin' structure, the parts being positively locked.

when the locking bar is in the position shown-in Fig. 4. V The locking bar 54 maybe retracted and advanced by the opening 20. The fiange 42 has a pair of depressions" v 'one side of the pin is enlarged, that is, broadened as shown at 52, and the slot is similarly broadened on-the opposite side of the pin, the broadened part'being' the 7 end oflthe slot on the opposite side. As can be;seen, therefore; the head or knob 29' of theppin fis'divided into 7 two parts 29a and 2% by virtue of the slot, the pin being resiliently compressible so that the two halves 29a and 29b may contract toward each other. V Vhen the knob 29 *is pu'shed'into or pulled from the receptacle. 27, the parts 29a and 29b are moved toward each other so that the knob will 'be contracted suificiently to permit it to offset portion overlying the other as shown, to form the tip 59." In the intermediate portion of thelocking bar is a longitudinal slot 58." In the broader portion of the locking barfare two similar apertures 61 and 62=on the center line of the locking bar, which form apart of'a detent mechanism, as will be described. The locking bar 54 is'shown inposition in the sleeve 3 9. and V within theprojection'18-in'Figs; 4 and 6. As may be I seen in these-figures, the' projection18 is retained in the sleeve39by rivets 64 and 65, the; ends of which extend into the slot 58 of lock; bar 54and forma guide for the lock bar; Within the'projection 18 at the knob or'head endthereofthere is inserted a length of plastic tube 66 which engages the portion of'the locking bar 54padjaccnt means of an'operating lever 69, having'a horizontally extending toe extending between the fingers57 of the locking bar 54, as 'shown in Fig; 4.; The lever 69"is' mounted on the shaft 88 of operating knob 25 as may be seeninFig; l and Fig; 2550 that by turning this knob fina clockwisedirectioni (looking at'Fig. 4), the. toe 70 would be moved similarly. to retract'the locking bar 54' in the sleeve 39.- The'pin 18 is mounted in sleeve 39 with slot 50in a verticalposition, so that any vertical disalignment-of'the door with the receptacle27 'does not cause the head 29 to be compressed as it'ent'ers'the opening 28. A r

It is highly desirable that the locking bar 54 have well defined; and predetermined locking and unlockingpositions and that'the operator when manipulating the knob 25, be able to determine from the force required'tojturn the knob, what positions the locking bar 'is'in. ;Accord-" V ingly, spring detent' mechanism-is provided for the locking bar 54 to provide'well defined locked and-unlocked positions.--. The spring 'detent mechanism is shown in cross-section in Fig. 5; As will be observed,'the sleeve 39 adjacent its inner end hasoppositelydisposed apertures 73 and 74in its opposite sides, and the two apertu'res61 and 62in the locking bar 54 can be moved into 7 l alignment with Qthe apertures 73.and 74. Nume'ral 76 designates a resilient split ring membenwhich' surrounds the 'sleeve'39 adjacent the apertures 73 and 74, and the ring 76 ha s vsiinilarslightly smaller apertures 77 nms positioned to register with the apertures 73 and' 74 in thesleeve 39. Numerals 80 and 81 designate a pair, of spherical'ball's which, inthe'position shown'inFig'. 5.,

engage partly inthe openings or apertures 73 and 74 thefs leeve 39 their outer 'facepo rtions engaging in the apertures -77- and 78 in the resilient split ring 76, and their inner face portions engaging. the aperture 62 in V V the lock bar 54; Inasmuch as, the split ring 76 resilient,

The

being formed from spring material, as can be seen, it urges the balls 8-9 and 81 against the peripheries of the aperture 62 in the lock bar 54 so as to hold the lock bar in the position in which it is shown. When the lock bar 54 is retracted, that is, moved to the left in Fig. 4, the balls 89 and 81 disengage from the aperture 62 and are thrust outward slightly against the force of the member 76, and their inner surfaces ride on the fiat sides of the lock bar 54 until the other aperture 61 becomes aligned with the balls 80 and 81. The spring member 76 then urges the balls inwardly again into engagement with the peripheries of the aperture 61 so that the position of the lock bar 54 is determined and well defined. In other words, the structure just described forms a spring detent mechanism which defines the locked and unlocked positions of the lock bar 54.

The sleeve 39 has a pair of apertures 83 and 84 which have a purpose that will presently be described.

In order for the knob 29 to latch and to be locked in the receptacle 27, the opening 28 of the receptacle plate or washer 30 is vertically elongated as shown in Fig. 9, or in other words, the opening is narrowed in a horizontal direction. The side portions of the opening 28 are defined by arcuate walls or lips 86 to engage the diametrally opposed faces of the knob parts 29a and 29!) when the largest diametral portion of the knob 29 has passed through the opening 28 and is expanded in that portion of the receptacle lying interiorly beyond the lips or walls 86, provided by the plate or washer 30. In other words, in order for the knob 29 to pass through the opening 28, its two halves must be compressed together by reason of the shorter horizontal dimension of the opening. Having passed through the opening, the knob expands, and as may be seen, if the lock bar 54 is then advanced so that its tip 59 lies in the slot or opening between the two halves 29a and 29b of the knob 29, it cannot then be compressed or contracted, and therefore cannot be withdrawn or retracted from the receptacle 27. The parts are thus firmly locked together.

Referring now to Figs. 1, 2 and 3 of the drawings, it

will be seen that the inner end of the sleeve 39 and the lock bar 54 extend into the cavity 24 in the door 12 between the flanged cup members 22 and 23. As may be seen, the operating knob 25 has a stem 88 extending through the cup 22 on which is carried the operating lever 69, and it is held in place by a cotter pin 89. The cup 23 has two inwardly extending pins 913 and 91 which lie on a vertical diameter of the cup and which are tapped to receive screws extending through the inner face of the cup member 22 (see Fig. 2). designates a leaf spring which has an intermediate portion with an extending tip 95 adapted to engage in one of the openings 83 or 84 in the sleeve 39, and this leaf spring has extending legs, the ends of which are attached to the inner surface of cup 23 at the inner ends of the pins 90 and 91. The purpose of this leaf spring is to facilitate the assembly of the parts, that is, particularly to assemble the cup 23 in the cavity with the pins 90 and 91 vertically aligned, so that the screw holes in the cup 22 can be conveniently aligned with the pins. Also, as previously pointed out, the operating knob assembly and cups are reversible so that the locking and unlocking of the door can be either from one side or the other, that is, if the cups 22 and 23 are interchanged in the cavity 20, and for the knob 25 to operate in the same relative manner, the lever 69 will extend in an upward direction and its toe 70 will engage between the fingers 56 of the lock bar 54 rather than between the fingers 57 as shown in Fig. 4.

The halves of the cups 22 and 23 farthest from the edge of the door are deeper as shown, and to provide a pleasing and ornamental escutcheon design, similarly shaped cover plates are provided as indicated at 97 and 98, which fit over the bottoms of the cups 22 and 23-, as may be seen in Figs. 2 and 3.

Numeral 94 The invention provides a feature whereby, if necessary in an emergency, the door can be unlocked from the inside without access to the knob 25. The back cup 23 and its cover plate have a central opening as shown at 99, through which a sharp pin or other member may be inserted and brought into engagement with the rivet opening 55 at the end of the lock bar 54, and the lock bar can be retracted in this manner for unlocking the parts. I

Referring now to Fig. 10 of the drawings, there is shown a modified form of the invention wherein the door or comparable part may be separately locked and unlocked from either side of the door. This modification is similar to the previous modification except that the two parts of the locking bar 54 are not attached together; in other words, the two parts are separate, forming two separate locking bars, each of which may be individually advanced and retracted for locking and unlocking. The tips of the two locking bars are identified as 59 and 59 and either may be inserted or advanced into the slot of the pin 18 for locking. The parts of the two locking bars are similarly numbered, the numbers on one of the parts being primed. The locking bars are assembled in the pin 18 and sleeve 39' as in the previous modification, and the locking bar 54 is operable by the knob 25 as described in connection with the previous modification. In the present modification a similar operating knob 25' is provided which is mounted in a cup, the same as the knob 25 is mounted as in the previous modification. The knob 25' carries an operating lever 69 having a toe 7b which cooperates with the fingers 57 of the locking bar 54. It will be observed therefore that the locking bar 54' can be individually advanced and retracted for locking and unlocking, as described in connection with the previous embodiment. Thus the door may be separately locked and unlocked from either side thereof, independently of the other side.

As will be observed by those skilled in the art, the invention provides a device for latching parts together and for positively locking them, the locking mechanism having predetermined and well defined locking and unlocking positions. The positions are defined and determined by a very simple but efiective detent mechanism occupying a minimum of space, and therefore not adding to the bulk of the assembled mechanism. The parts are characterized by simplicity of construction and assembly but yet providing for firm and positive latching and locking operations.

The foregoing disclosure is representative of a preferred form of the invention. It is to be understood that various modifications and alternatives thereof may be adopted by those skilled in the art, and it is intended, accordingly, that the disclosure be interpreted in an illustrative rather than a limited sense, the scope of the invention to be in accordance with the claims appended hereto.

1 claim:

1. In a device for separably attaching relatively movable parts, in combination: means comprising a projection extending from one part; means having an opening in the other part adapted to receive and retain the projection, the projection having means operable to releasably engage the opening in a manner requiring force to withdraw the projection; means movable to a position wherein the projection is positively held in engagement with said opening; and spring detent means providing predetermined locked and unlocked positions of said movable means, said spring detent means comprising mechanism including a resilient member providing interengagement between the first means and the movable means.

2. in a device for separably attaching relatively movable parts, in combination: means comprising a tubular projection extending from one part; means having an opening in the other part adapted to receive and retain the projection, the projection having means operable to releasably engage the opening in a manner requiring force "7 to withdraw the projectionymeanscomprising a:locking bar extending within the tubular'projection andniovable to a position wherein the projection isv positively held in engagement with said opening; and spring 'detent means including a resilient member providing interengagement between said first means and said locking bar whereby said locking bar has predetermined locked and unlocked positions. f 3 In a device for 'separably attaching relatively movable parts, in combination: means comprising a tubular projection extending from one part; means having an opening in the other part adapted to receive and retain the projection, the projection having means operable to releasably engage the opening in a manner requiring force to Withdraw the projection; means extending within the tubular projection and movable to a position wherein the projection is positively held in engagement with said opening, detent means comprising a resilient spring member around .said first means; and balls engaged between said member and said extending means, said extending means having ball engaging formations whereby said. detent means defines locked and unlocked positions of said extending means. V I V r 7 4. in adevice for separably attaching relatively movable parts, means comprising a tubular projection extend ing from one part and adapted to be received in the other part, an advanceable and retractable'bar. within the projection; detent means comprising a circular-resilient spring member around the first means; and'balls engagedbetween the spring vmember and the said bar,

members for. said opening; and resilient means extend.- ing from 'oneofsaid closure" members and engageable with said first means at a predetermined angular position of said one closureimember to pr ovide aipredeterrnined "orientation as betweensaid one'closure meinber and said firstmeans.

s ,8. ,In a devicregfor separably attaching relatively mov V able parts such as a sliding door and d oonframei and the like, in combination: meanscomprisingatubular projection extending 'from 'one part and adapted tofbe received in the other, part, saidjone part having a transverse opening into which said first means extends;1closure members adapted to be received in said opening, one'of detent. means defines predetermined extended and retracted positions of said bar. a

5. In a device for separably attaching relative movable parts, in combination: means comprising a tubular projection extending from one part and adapted to be received in the other part; a reciprocatable bar disposed longitudinally in the said member spring detent means 1 associated with the bar, comprising a circular resilient split ring disposed around said first meansjsaid'first means having c'omplementarily disposed apertures, in its side Walls, said ring having similar registering apertures and a pair of ball 'members'disposed on opposite sides of the ,bar,lthe inner surfaces of the ball members engaging in an aperture in the bar member and the outer surfaces extending through the apertures in the first means and engaging the apertures in the split ring, the said ring normally applying an inward force against the ballrnembers. V

' 6. In a device for se'parably attaching relatively movable parts, inlcombination: means comprising a projection extending from one part; means havingan opening means, said manual operating knob havingan actuating I member engageable with said movablefmeans and said movable means having oppositely extending similarly 7 formed portions engageable with said actuating memberin two different positions thereof, whereby said assembly is reversible so that the manual operating knob can be mounted to be operated from either side of the said one part.

I 7. In a device for separably attaching relatively. mov able parts such as a sliding door and door frame and'the like, incombination: means comprising a tubular projection extending from one part and adapted to be received in the other part; a transverse opening in the one part, into which the; first vmeans extends;.closur e said closure members having attaching means extending therefrom and adapted to'be attached to the otherclosure member; and said one closure memberhavingja resilient fingers attached thereto, engageable with said first means to providefororienting said one closure member in a predetermined position adapted 'forfa'ttaching it to the other closure member.

9. In a device for separably attachingrelatively movableparts such as a slidingdoor and door frame and the like, in combination: means comprising a tubular projection extending from one part, said one part having a transverse opening into which said tubular projection extends, closure members for said opening, one

ofsaid members carrying a manual operating knob associated'with said tubular projection, the said tubular projection having a reciprocatable member therein, actuatable by said manual operating knob, and saidother closure member having a relatively small central opening whereby access may be had to said reciprocatable member by means of aninstrumentextended through said central opening'for actuating said reciprocatable member. V 10. Ina .devicefor separably; attaching relatively movable parts, in combination: means comprising a tubular projection extending from one part; means having an opening in the other part adapted to receiveand retain the projection; means within the projection movable to a position wherein the projection is positively held in engagement with said opening, said last means comprising a bar and'spring' detentmeans associated therewith,

said spring detent means'comprising a resilient member extending aroundsaid first means and ball members en gaged between saidresilientjmember and said bar, and said bar having ball engaging'formations whereby said detentmeans defines predetermined extended and ;re-. tracted positions of said bar; 7 f

11. In a device for separably attaching relatively movable parts, in combination: means comprising a projection extending from one part; means having an opening inthe other part adapted to receive and retain the pro jection; means including a pair of locking ,members within the projection, each of which is movableto a position wherein the projection is,positively held in 'ehgagement with said openingand means includingoper ating devices on opposite side'sof said one part, each of which is operable to actuate o'neof said locking members.

12. In a device for separably attaching relatively movable parts, in combination; means comprisinga tubular projection extending from one part; means having an opening in the other part adapted to'receive and retain "the projectionjmeans comprising a pair oflocking bars within the projection, each of which is movable to .a

position wherein the projection is positively held in engagement with said opening; and means comprising operatingdevices on oppositesides of s aid one part, each of said devices being arranged to beoperable to actuate one of said locking bars. a t 13. In a device for separably able parts, in combination: means comprisingaprojec- 'tion extending from onepart; means having anfopeiiing" in the other part adapted to receive and retain the 7pm,- jectiong'means including a pair of locking-members withattaching relatively mov V in the projection, each of which is movable to a position wherein the projection is positively held in engagement with said opening; means including operating devices on opposite sides of said one part, each of which is operable to actuate one of said locking members; and spring detent means associated with said locking members defining predetermined locked and unlocked positions of the members.

14. In a device for separably attaching relatively movable parts, in combination: means comprising a tubular projection extending from one part; means having an opening in the other part adapted to receive and retain the projection; means comprising a pair of locking bars within the projection, movable to a position wherein the projection is positively held in engagement with said opening; means for individually actuating said locking bars; and spring detent means comprising a circular resilient member around said first means and ball members engaged between the resilient member and the locking bars, the locking bars having ball receiving formations whereby the detent means defines locked and unlocked positions of the locking bars.

15. In a device for separably attaching relatively movable parts, in combination: means comprising a projection extending from one part; means having an opening in the other part adapted to receive and retain the projection, the projection having means operable to releasably engage the opening in a manner requiring force to withdraw the projection; means including a pair of members each of which is movable to a position wherein the projection is positively held in engagement with said opening; and means whereby said members are individually operable from opposite sides of said one part.

16. In a device for separably attaching relatively mov able parts, in combination: means comprising a projection extending from one part; means having an opening in the other part adapted to receive and retain the projection, the projection having means operable to releasably engage the opening in a manner requiring force to withdraw the projection; means comprising a pair of members within the projection, each of which is movable to a position wherein the projection is positively held in engagement. with said opening; and spring detent means providing predetermined locked and unlocked positions of said movable means.

References Cited in the file of this patent UNITED STATES PATENTS Wallace Feb. 27, 

